Series of sewers or conduits



1,572,197 Feb' 9 1926' w. c.. FERGUSON SERIES OF' SEWERS OR CONDUITSFiled April 14. 1922 2 Sheets-Sheet 1 f S"\"I\` f mi wn 1p,

TrOEN/sms Feb. 9', 1926. 1 1,572,197 A w. c. FERGUSON f SERIES 0F sEwERs0R GONDUITS Filed April 14. 1922 z sheets-shan 2' 27V VEN Toe #Trae/v5YS Y sewers.

Patented Feb. 9, 1926.

UNITED STATES WILLIAM C. FERGUSON, 0F SvTLLOUKIS, MISSOURI.

SERIES OF SEWERS OR CONDUITS.

Application filed April 14, 1922. Serial No. 552,579.

To ZZ eli/01m t may concern.'

Be it known that I, lViLLiAM C. FERGUSON,l

a citizen of the United States, residing at St. Louis, Missouri, haveinvented a certain new and useful Improvement in Series of Sewers oi'Conduite, of which the following is a full, clear, and exactdescription, such as will enable others skilled in the art to which itappertains to make and use the Slll'le.

This invention relates to sewers, conduits and other tubular structuresot the kind that comprise Va double circular wall whose inner portion iscomposed of segmental blocks or tile. In building double wall structuresot the general type referred to in which the outer and innei` portionsot the wall are composed of outer and inner segmental blocks or tilearranged in interlocking rela- -tion it is now the universal custointovary the dimensions of. both the inner and outer blocks when thediameter of theI structure is to be varied. For example, it the conduitto be constructed is to have a diameter ot 72 inches, it is the practiceto use inner blocks having an inside width of 11.01 inches and outerblocks having an Vinside width of 11.40 inches, and if the conduit to beconstructed is to have a diameter of 54 inches, it is. the practice touse inner blocks having an inside width of 10.28 inches and outer blockshaving an inside width of 10.72 inches. Also in structures where theinner portion of the circular wall is composed ot segmental tile and theouter portion of the wall is constructed ot diierent material it is thecustom to use diiierent sized blocks or liners for diiterent sizedAccordingly, the cost of building sewers and conduits of the generaltype above referred to is increased considerably by reason of the largenumber of dies that. are required to L-form the different sized blocksor tiley and by reason ot the large stock ot' blocks ortile it isnecessary to keep on hand to supply orders Jfor sewers of conventionalsizes ranging from 30 inches to 72 inches in diameter, with a variationof 3 inches between the ditferent sizes. Moreover, the above method ofconstructing sewcan beused only in the construction of a sewer ot thatdiameter, or approximately that diameter.

The present almost .universal practice in sewer construction is for theuse of sizes' varying trom each next size larger or smallf.

er by 3 inches, and one object of this in; vention is to provide amethod ,of construct.- ing a double lwall sewer or conduit, by which theaddition of one unit to a standard `size sewer will give the nextstandard size sewer without the necessity of providing speciallydesigned blocks torthe different sizes. Y

Another object is to provide a method of constructing double wallsewers, conduits and the `like which reduces the number of variableelements on such structures, 0r, in other words, reduces the numberofditferent sized blocks that are required in the e011-,

struction of a series of sewers of conventional diameters, say,rtorexample, lifteen sewers ranging from 30 inches to 72 inches in ameter. l

Another object is to provide a method of constructing double wall sewersor conduits that permits great iiexibility in'construction, so that whengreater loads are encountered, the required strength may be obtainedsimply by a' different arrangement of the various units, thus overcomingthe necessity.l of re-designing the individual units to meet eachdifferent condition. f

And still another object is to provide an inner block or tile for sewersyor conduits which is soproportioned and designedthat it is capable ofbeing usedwith all of thel various sizes of sewers which are nowstandard, namely, sewers in which the variation in diameter between thedifferent sizes is 3 inches. f

To this end I have devised a method of constructing a series ot doublewall sewers or conduits of different diameters, that is characterized byusing a universal inner block or tile ot standard shape and dimensionsfor all sewers oit' the series.v

Figure 1 otv the drawings is a diagrami matic view, illustrating myinvention applied to a double wall sewer or conduit whoseV inner andouter portions are composed ot segmental tile; and Figures 2, 3,4 and 5are sectional views, illustrating the construction of the universalinner blocks and the different sized outer blocks used in the:construction ot the ditferent sized sewers that make up thecomand anouter portion that surrounds said inner tile. In the form of: myinvention herein ilflustratedthe outer -portion of the wall is composedof outer segmental blocks arranged in interlocking relation with ,the

innerblocks with the joints and spaces. between said blocks lled withmortar, cement or the-like. I wish itftol be understood, however-, that'it is' immaterial, so far as my broad idea is concerned, how the outerlportion of the wall of the sewer is constructed,

selon-g as thenimier yportion of the wall is constructed of universalsegmental blocks orf standard dimensions that are capable of usewith-anyofthe various sized sewers of the entire series The inner blocksrA usedin all of the fifteen ditlerent sized conduits of.' the series are ofthe same shape and dimensions, and therefore, will? be referred to asuniversal inner blocks. In a structure of the particular` type hereinshown the outer blocks used in the different sized conduits are-vofdifferent dimensions, however, andi constitute set or group of differentsized blocks. For example, one outer block B1 of the set `or group,having. certain dimensions, can be used to construct conduits rangingindiameter from 30 inches as a mini-mum to 42 inches as an ordinarymaximum, another outer blocl; Bfof the set, havingdifferent.,dii'nensions, can be used to construct conduitshavingdiametersranging and vary-` I block B?" having different dimensions,can.

be used to form conduits ranging and varying indiameter by 3 inches froman ordinary minimum; diameter of 5l linches to an ordinary maximumdiameter of inches, and another outer block 'B3 ofthe set havingdifferent dimensions, can` be used to construct conduits having anordinary minimumdiameter of 60 inches andl varying by 3f inches up to anordinary maximum diameter of 72 inches, l i

I'V'hile thel outer blocks yconstitnti-ng the set differ in dimensions,they Vare of the samer general design, in that each is provided on. itsinner side with a lonfgitudinalily-disposed: center groove A1 that is`adapted toreceive long-itudinally-extending side ribsQ on two adjacentinn-er blocks A, the spaces and joints between the co-operating surfacesof the inner and outer blocks-'of the structure being filled withcement, mortar or other suitable material. IVhatever type of structurethe universalinner'blocks A are used `with, each o-f said blocks A mustbe of a certain width, it must bek provided with a concaved innersurface 3 of a certain curvature and it must-*be provided withlongitudinal side edges i that are disposed in a certainrelation totheinner surface 3 of the block. f In order that the blocks A will beuniversal. for all-sizes of sewers usedl in common practice,the threeelements above mentioned must bev governed by certain principles.rlihus, the width of the face 3 of each of the inner blocks A mustbesuch that when twenty-four of' such `block-s are assembled around acircular form, they will form a cylindrical shell having a diameter of72 inches g1 when twenty-three ofL said inneir blocks are assembledaround a circular form,

they will. form a cylindrical shell hai/ing diameter of 69l inches etc.,the elimination orsubstraction of one inner block decreasing theydiameter of the .conduit-or structure by 3 inches.. Accordingly, thevwidth ofthe face of the universal inner bl'ocl: 'A between thelongitudinal side edges t must bey theoretically three times. pi or914248 inches,A

butinasrnuclr as there is lalways a. vari-ation inthe shrinkage of theclay material from which the blocks are `usually formed, a certainallowance must be made sov that in actual practice theV width of theuniversal block-A between the side edges 4 of same will be three timespi, minus'a unit which is' equal to the extreme variation of theshrinkage of material used inthe construction-of the) block.

Another important :point in the design of. the universal block A is theangle of the side edges 4 of said block, it being necessary to have saidside edges disposed at such ali-angle.v withrelation. to th'exinnersurface 3 of the block that irrespective of the' size of the conduitV inwhich the blockis used, it fwilili not. arch at its outer edge,y andthus crea-te ainunstable arch structure.r The engineering requirementswithL respect to `the,

edges 4 in their relation to the edges of ani adjacentblock is thatunder all conditionsy the opposed edges must either be parallelor sodisposed with relation to eaclr other .th-at they will arch at' their.inner elementtudinal` side edges oftwo adjacent inner bloe-ltsqwilll besubstantially wedge-shaped,

Wil

with the inner elements of the edge a forming the apex of the wedge.This can be accomplished conveniently by providing the universal blockArwith longitudinal side edges 4f that are parallel, or approximatelyparallel, to the radius of the largest conduit of the series, as shownin Figure 5.

Another important characteristic of the universal block A is the radiusof its inner face 3. y Preferably, the radius o-f said face is as nearas possible to the mean between the two extreme sizes for which theblock is to serve. There is a certain deformation during the process ofburning or firing blocks of this general shape. Some blocks will becomeflatter than they originally were and some will warp and have a greatercurvature than they had when they came out of the dies. As a result ofthis phenomenon, hy assorting the blocks and using those which havetaken on the greatest curvature for building the smaller sizes ofconduits, using those which have not become distorted in burning tobuild the middle sizes and using those that have become flattened tobuild the larger sizes, a very much better finished structure willresult than is possible with the present method, where it is necessaryto use each block in a particular sized conduit, even where that blockis either more dish-shaped orflattened more than is desired.

lVhen the outer portion of thewall of the structure is composed ofsegmental outer blocks or tile, as herein illustrated, there are twothings which are important to the flexibility of construction and to thestrength of the structure. There may be as many sizes of these outerblocks as the local conditions make necessary. ln Figure l of thedrawings I have shown four different sizes of outer blocks that areadapted to be used in the construction of fifteen sewers or conduitshaving different diameters. @ne important characteristic of said outerblocks is that they must be of such dimensions that when they areassembled the spaces between the` longitudinal side edges of same willbe wider than the spaces between the longitudinal side edges 4e of theinner blocks A, thereby pern'iitting interchangeability and insuring theinner blocks A arching before the outer blocks arch, in case the form isremoved before the mortar or concrete between the blocks has set, andconsequently, eliminating the possibility of some of the inner blocks atthe top side of the structure dropping out of position, as might occurif the outer blocks arched before the inner blocks. To state it inanother way, it is essential that the outer blocks B, B', B2 and B3 beof such width with relation to the width of the inner blocks A that theinner blocks A- will arch or come together immediately upon the removalof the form on which thev inner blocks are laid up, and thus sustain`the weight of the outer blocks at the top side of the structure, itbeing the usual custom to remove the form before the mortar or concretei has set.

W'hen the outer blocks are made in the form of hollow tile provided withlongitudinally-extending webs 5, it is preferable to thicken or increasethe cross-sectional area of said webs adjacent the inner and outer endsof same, as indicated by the reference character 5 in Figures 3, 4 and5, as this practice by simply arranging the units in' 'different ways.For instance, a 57 inch sewer would ordinarily be built from innerblocks A and outer blocks B2. If, however, the sewer is to be built inalocation where it is subjected to greater loads than a 57 inch sewer isusually subjected to, the strength of the sewer can easily be increasedby usingI outer blocks B3 in place of the blocks B2, it being noted thatthe sets or groups of outer blocks B, B', B2 and B3 are of gradually increasing thickness. On the other hand, if as in drainage work, the loadtowhich the sewer will be subjected will be exceptionally light, thesewer can be constructed from inner blocks A and outer blocks B, thuseffecting a considerable saving in the costof construction.

Having thus described my invention, what I claim as new and desire tosecure by Let.- ters Patent is:

l. A method of constructing double wall sewers or conduits whosediameters vary in a. certain ratio, characterized by forming the innerportions of the walls of the sewers from universal blocks of standarddimensions and forming the outer portions of said walls from outerblocks that vary in thickness according to the diameter of the sewerbeing constructed, and increasing the number of inner blocks and thenumber of outer blocks by one when a sewer of the next largerysize isbeing constructed.

2. A system of constructing a series of double wall sewers or conduitswhose diameters vary in a certain ratio, characterized by forming theinner portion of the wall of each conduit of. the series from universalsegmental blocks of standard dimensions and forming the outer portionsof the y the.E external 3 leadi; mpesed: 0n the conduit.

A' conduit' orl sewer." formmg one.v O- a..

by: three inches-5. said conduit! having 'w douofriL s mentali n'uerblocks propovti(medz so as t Vbe capable ofuse inzthe eonstl'uctn .off Ycendmts 'of 21;.: dlffelfent. size andwhose nuten 10 portion; isconstr-ueted's of" segmental 'Guten blocks; ofi a `fheknessidifferentfrom; the thickness of: :the outer'bloeksused in; ne cond vuit off amaterially: dfe-Ient size;

WILLIAM- C. E-ERGUSQN.

